Shopify App Development

When to use this skill

Use this skill when:

• Creating a new Shopify app
• Building app extensions (admin, checkout, etc.)
• Embedding UI in the Shopify admin
• Working with OAuth and app authentication
• Managing webhooks and app events
• Using Shopify Polaris UI components
• Deploying apps to the Shopify App Store

App Types

Public Apps

• Distributed via the Shopify App Store
• Available to all merchants
• Require app review process

Custom Apps

• Built for a single merchant/organization
• Direct installation (no app store)
• Simpler distribution

Sales Channel Apps

• Integrate a sales channel with Shopify
• Appear in the Shopify admin’s sales channels

Getting Started

1. Create a New App

# Initialize a new app
shopify app init

# Choose a template:
# - Remix (recommended)
# - Node
# - Ruby
# - PHP

2. Project Structure (Remix Template)

my-app/
├── app/
│   ├── routes/
│   │   ├── app._index.jsx      # Main app page
│   │   ├── app.products.jsx    # Products page
│   │   └── webhooks.jsx        # Webhook handlers
│   ├── shopify.server.js       # Shopify API config
│   └── root.jsx                # Root layout
├── extensions/                  # App extensions
├── prisma/                      # Database schema
├── shopify.app.toml            # App configuration
└── package.json

3. Start Development

# Start dev server with tunnel
shopify app dev

# View app info
shopify app info

App Configuration

shopify.app.toml

name = "My App"
client_id = "your-api-key"

[access_scopes]
scopes = "read_products, write_products, read_orders"

[webhooks]
api_version = "2025-01"

[[webhooks.subscriptions]]
topics = ["products/create", "orders/create"]
uri = "/webhooks"

[app_proxy]
url = "https://myapp.example.com/proxy"
subpath = "app-proxy"
prefix = "apps"

Environment Variables

SHOPIFY_API_KEY=your-api-key
SHOPIFY_API_SECRET=your-api-secret
SCOPES=read_products,write_products
HOST=https://your-tunnel-url.ngrok.io

Authentication

Session Tokens (Recommended)

Apps embedded in the Shopify admin use session tokens:

// app/shopify.server.js
import "@shopify/shopify-app-remix/adapters/node";
import { AppDistribution, shopifyApp } from "@shopify/shopify-app-remix/server";

const shopify = shopifyApp({
  apiKey: process.env.SHOPIFY_API_KEY,
  apiSecretKey: process.env.SHOPIFY_API_SECRET,
  scopes: process.env.SCOPES?.split(","),
  appUrl: process.env.SHOPIFY_APP_URL,
  distribution: AppDistribution.AppStore,
});

export default shopify;

Admin API Access

import { authenticate } from "../shopify.server";

export async function loader({ request }) {
  const { admin } = await authenticate.admin(request);

  const response = await admin.graphql(`
    query {
      products(first: 10) {
        nodes {
          id
          title
          handle
        }
      }
    }
  `);

  const data = await response.json();
  return json({ products: data.data.products.nodes });
}

App Extensions

Extension Types

Create an Extension

# Generate an extension
shopify app generate extension

# Choose extension type from the list

Admin UI Extension Example

// extensions/admin-block/src/BlockExtension.jsx
import {
  reactExtension,
  useApi,
  AdminBlock,
  Text,
  BlockStack,
  InlineStack,
  Button,
} from "@shopify/ui-extensions-react/admin";

export default reactExtension("admin.product-details.block.render", () => (
  <ProductBlock />
));

function ProductBlock() {
  const { data } = useApi();

  return (
    <AdminBlock title="Custom Block">
      <BlockStack>
        <Text>Product ID: {data.selected[0]?.id}</Text>
        <InlineStack>
          <Button onPress={() => console.log("clicked")}>Action</Button>
        </InlineStack>
      </BlockStack>
    </AdminBlock>
  );
}

Theme App Extension

// extensions/theme-block/blocks/product-rating.liquid
{% schema %}
{
  "name": "Product Rating",
  "target": "section",
  "settings": [
    {
      "type": "product",
      "id": "product",
      "label": "Product"
    }
  ]
}
{% endschema %}

<div class="product-rating">
  <app-block-rating product-id="{{ block.settings.product.id }}">
  </app-block-rating>
</div>

{% javascript %}
  // Your JavaScript here
{% endjavascript %}

{% stylesheet %}
  .product-rating {
    padding: 16px;
  }
{% endstylesheet %}

Polaris UI Components

Basic Layout

import {
  Page,
  Layout,
  Card,
  Text,
  BlockStack,
  InlineStack,
  Button,
  TextField,
  Select,
  Banner,
  List,
} from "@shopify/polaris";

export default function ProductPage() {
  return (
    <Page title="Products" primaryAction={{ content: "Create product" }}>
      <Layout>
        <Layout.Section>
          <Card>
            <BlockStack gap="300">
              <Text as="h2" variant="headingMd">
                Product Details
              </Text>
              <TextField label="Title" value={title} onChange={setTitle} />
              <Select
                label="Status"
                options={[
                  { label: "Active", value: "active" },
                  { label: "Draft", value: "draft" },
                ]}
                value={status}
                onChange={setStatus}
              />
            </BlockStack>
          </Card>
        </Layout.Section>

        <Layout.Section variant="oneThird">
          <Card>
            <Text as="h2" variant="headingMd">
              Summary
            </Text>
          </Card>
        </Layout.Section>
      </Layout>
    </Page>
  );
}

Data Table

import { IndexTable, Card, Text } from "@shopify/polaris";

function ProductTable({ products }) {
  const rowMarkup = products.map((product, index) => (
    <IndexTable.Row id={product.id} key={product.id} position={index}>
      <IndexTable.Cell>
        <Text variant="bodyMd" fontWeight="bold">
          {product.title}
        </Text>
      </IndexTable.Cell>
      <IndexTable.Cell>{product.status}</IndexTable.Cell>
      <IndexTable.Cell>{product.inventory}</IndexTable.Cell>
    </IndexTable.Row>
  ));

  return (
    <Card>
      <IndexTable
        itemCount={products.length}
        headings={[
          { title: "Product" },
          { title: "Status" },
          { title: "Inventory" },
        ]}
        selectable={false}
      >
        {rowMarkup}
      </IndexTable>
    </Card>
  );
}

Webhooks

Register Webhooks

# shopify.app.toml
[[webhooks.subscriptions]]
topics = ["products/create", "products/update", "products/delete"]
uri = "/webhooks"

Handle Webhooks

// app/routes/webhooks.jsx
import { authenticate } from "../shopify.server";

export async function action({ request }) {
  const { topic, shop, payload } = await authenticate.webhook(request);

  switch (topic) {
    case "PRODUCTS_CREATE":
      console.log("Product created:", payload.id);
      // Handle product creation
      break;
    case "PRODUCTS_UPDATE":
      console.log("Product updated:", payload.id);
      // Handle product update
      break;
    case "ORDERS_CREATE":
      console.log("Order created:", payload.id);
      // Handle new order
      break;
  }

  return new Response("OK", { status: 200 });
}

Metafields

Reading Metafields

const response = await admin.graphql(`
  query {
    product(id: "gid://shopify/Product/123456") {
      metafield(namespace: "custom", key: "care_instructions") {
        value
        type
      }
      metafields(first: 10) {
        nodes {
          namespace
          key
          value
          type
        }
      }
    }
  }
`);

Writing Metafields

const response = await admin.graphql(
  `
  mutation metafieldsSet($metafields: [MetafieldsSetInput!]!) {
    metafieldsSet(metafields: $metafields) {
      metafields {
        key
        value
      }
      userErrors {
        field
        message
      }
    }
  }
`,
  {
    variables: {
      metafields: [
        {
          ownerId: "gid://shopify/Product/123456",
          namespace: "custom",
          key: "care_instructions",
          value: "Machine wash cold",
          type: "single_line_text_field",
        },
      ],
    },
  },
);

Deployment

Deploy to Shopify

# Deploy app and extensions
shopify app deploy

# Deploy specific version
shopify app versions list
shopify app release --version VERSION_ID

App Store Submission

1. Complete Partner Dashboard app listing
2. Add required app store assets
3. Submit for review
4. Address review feedback
5. Publish approved app

CLI Commands Reference

Best Practices

1. Use session tokens – More secure than API keys
2. Handle rate limits – Implement retry logic
3. Validate webhooks – Verify HMAC signatures
4. Test on dev stores – Use development stores
5. Follow Polaris guidelines – Consistent UX
6. Monitor app health – Track errors and performance

Resources

• App Development Docs
• Polaris Components
• App Bridge
• Admin API Reference
• App Store Requirements

For backend functions, see the shopify-functions skill. For checkout customization, see the checkout-customization skill.